In electrophotographic applications such as xerography, a charge retentive surface is electrostatically charged, and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as "toner". Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charged surface may be imagewise discharged in a variety of ways.
Although a preponderance of the toner forming the image is transferred to the substrate during transfer, some toner invariably remains on the charge retentive surface, being held thereto by relatively high electrostatic and/or mechanical forces. It is essential for potimum operation that toner and debris remaining on the surface be cleaned thoroughly therefrom. In addition to such toner and debris, a film build up is noted of material not removed by standard cleaning techniques.
Blade cleaning is a highly desirable method for removal of residual toner from a charge retentive surface. In such an arrangement, a cleaning blade is provided and supported adjacent the charge retentive surface with a blade edge chiseling toner from contact with the surface. Subsequent to removal from the surface, toner is transported away from the blade area by a toner transport arrangement. Blade cleaning arrangements are very effective, inexpensive relative to other cleaning devices, and very serviceable over the device lifetime. Variations in lubricants and materials allow the use of blade cleaning at relatively high speed. Compared to brush cleaners, cleaning blades are less expensive and do not create the tirboelectric problems associated with brush cleaners handling electrostatically attractable powders.
Removal of accumulating toner from the blade area may be accomplished in a variety of ways, each dependent on the machine arrangement. While a cleaning arrangement for a cylinder or a vertical surface may allow toner to simply fall from the blade area to a toner transport device such as an auger, as shown for example in 4,648,705 to Tachibana et al., or US-A 4,593,997 to Fox et al., positioning the cleaning arrangement on a horizontal upwardly facing surface, sometimes referred to as twelve o'clock cleaning, requires removal of toner from the surface. Typically, toner might be removed from the blade area either by a brush arrangement which transports the toner to an auger arrangement for transport to another area, such as shown for example in US-A 4,427,289 to Oda and JP 61-77882 (A) to Saito or directly by an augering arrangement, such as shown for example in US-A 4,329,044 to Kitajima et al. Either arrangement serves to transport toner removed from the charge retentive area satisfactorily. Generally the auger edge in contact with the charge retentive surface is smooth to avoid damage to surfaces. Brush augering arrangements are known for removal of toner from fiber brush cleaners, as shown in US-A 4,213,794 to Woodling et al. and for carrying toner along toner transport paths as shown in US-A 4,054,381 to Bernhard and US-A 4,442,789 to Pirwitz.
Over periods of time, despite the cleaning action of the blade a buildup of residue or toner film on the charge retentive surface may be noted, manifesting itself as comets, spots, and other copy quality defects, on copies made in the device. This film may be removed from the surface with a slight abrading action. Of course, it will no doubt be appreciated that the abrasion must not be so rough as to damage the charge retentive surface, but must be adequate to remove the buildup of toner film. It has been noted that a foam roll may be constructed adequately in this regard. In operation, foam cleaning rolls have a tendency to collect toner in open pores in the foam. The toner seated in the pores abrades the charge retentive surface as it comes into contact therewith, effectively scraping the buildup of contaminants from the charge retentive surface.
Snelling, Xerox Disclosure Journal, Volume 5, No. 6, November/ December 1980, pp. 637, 638, shows an auger-shaped member which simultaneously cleans and carries toner from a charge retentive surface with a pumping action created by its rotation within a closed container. However, it does not appear to suggest use of advantageous blade cleaning methods which sealingly prevent toner from passing through the cleaning station, suggest that abrasion of the charge retentive surface is desirable, nor suggest that foam material used should be provided with toner collecting pores for abrasion of the charge retentive surface. Foam roll cleaning devices used alone suffer from difficulties in cleaning toner from the foam roll. Additionally, the high speed believed required by the device to create an air pumping action, and satisfactorily clean the surface of the charge retentive surface would be higher than desirable to avoid wear on the charge retentive surface. Bean, Xerox Disclosure Journal, Volume 1, No. 8, August 1976, page 67, demonstrates a foam rubber helical cleaning member, also deficient in these aspects.